1. Field of the Invention
The present invention relates to a radiation detection apparatus for irradiating a subject with radiation and capturing a radiation image, and to a radiation image capturing system that uses such a radiation detection apparatus.
2. Description of the Related Art
In the medical field, a radiation image capturing apparatus, in which radiation is applied to a subject, and radiation that has passed through the subject is directed to a radiation detection device for capturing a radiation image of the subject, has been widely used.
In this case, as types of radiation detection devices, there are known a conventional radiation film on which a radiation image is exposed and recorded, or a stimulable phosphor panel in which radiation energy is stored as a radiation image in a stimulable phosphor body, and when stimulating light is applied thereto, the radiation image can be read out as stimulated light. In such radiation detection devices, the radiation film in which a radiation image has been recorded is supplied to a developing apparatus where an image developing process is carried out, or the stimulable phosphor panel is supplied to a reading apparatus in which the radiation image is acquired as a visible image by performing a reading process thereon.
On the other hand, in a medical environment such as an operating room or the like, for performing rapid and precise treatments with respect to a patient, it is essential to read out and display the radiation image directly from the radiation detection device. As a radiation detection device capable of responding to such requirements, a radiation detection device has been developed that uses solid state detection elements, which convert radiation directly into electrical signals, or which, after the radiation has been converted into visible light by a scintillator, convert the visible light into electrical signals, which are read out.
In particular, in a transportable type of device, a battery for supplying electrical power to the radiation detection device and to various electronic circuits is accommodated inside of a casing in which the radiation detection device is housed. Generally, such a transportable device is referred to as an electronic cassette. In this type of electronic cassette, naturally, it is desirable to reduce the electrical power consumption of the battery.
In the aforementioned transportable type of electronic cassette in which a battery is accommodated, for example, as one method for reducing power consumption of the battery, the method disclosed in Japanese Laid-Open Patent Publication No. 2005-173432 has been proposed.
This method has the object of avoiding needless power consumption corresponding to the operative condition of the radiation cassette itself, and is equipped with a contact sensing unit and/or an orientation detection sensor (angle sensor, vibration gyro or the like) in a portion of the casing of the electronic cassette. In addition, during the time that contact is detected, the power supply is suppressed, and when contact with the electronic cassette is not sensed, an image capturing capable mode is enabled.
However, in the method disclosed in Japanese Laid-Open Patent Publication No. 2005-173432, since it is not known until the electronic cassette is set at a desired position, whether or not the electronic cassette is actually capable of capturing an image, and thus, there is a problem in that time may be required in order to replace the electronic cassette with a different electronic cassette.